Space Shuttle probabilistic risk assessment: methodology and application

This paper describes the methodology and processes used for the probabilistic risk assessment of the Space Shuttle vehicle to systematically quantify the risk incurred during a nominal Shuttle mission and rank the risk driving components to allow for a concerted risk and cost reduction effort. This year-long effort represents a development resulting from seven years of application of risk technology to the Space Shuttle. These applications were initiated by NASA shortly after the Challenger accident as recommended by the Rogers and Slay Commission reports. The current effort is the first integrated quantitative assessment of the risk of the loss of the Shuttle vehicle from 3 seconds prior to liftoff to wheel-stop at mission end. The study which was conducted under the direction of NASA's Shuttle Safety and Mission Assurance office at Johnson Spaceflight Center focused on Shuttle operational risk but included consideration of all the Shuttle flight and test history since the beginning of the program through Mission 67 in July of 1994.